1. Field of the Invention
The present invention relates to a through anchor used in a vehicle seat belt device.
2. Description of the Related Art
A webbing belt is a component in a seat belt device for restraining the body of an occupant seated in a vehicle seat. The webbing belt includes two ends in the longitudinal direction, one of which is anchored to a spool of a take-up device attached to, for example, the side of the seat, and the other being fixed to an anchor plate disposed near the take-up device. The webbing belt passes through a through hole formed in a through anchor disposed above the take-up device (e.g., at an upper side of a center pillar of the vehicle) and is folded downward at the longitudinal-direction central portion thereof.
The webbing belt also passes through a through hole formed in a tongue plate between the through anchor and the anchor plate. The webbing belt is pulled out from the take-up device by pulling the tongue plate, and is fastened by engaging the tongue plate with a buckle device disposed at the side of the seat opposite to the side at which the take-up device is disposed. In this manner, the body of the occupant is restrained by the webbing belt.
The through anchor includes a core metal in which a base opening of a through hole is formed. The core metal is covered entirely with a synthetic resin material, except for a portion used to attach the core metal to the vehicle center pillar. An inner peripheral surface of the base opening is also covered with the synthetic resin. The webbing belt thus contacts and slides on the synthetic resin material.
When the webbing belt slides on the synthetic resin material, friction is generated between the webbing belt and an inner peripheral surface of the hole formed in the through anchor. The friction is preferably as small as possible, in view of the ease with which the webbing belt can be pulled out when the occupant fastens the webbing belt around the occupant""s body or when the webbing belt is pulled out by the occupant""s body suddenly moving forward due to inertial force when the vehicle undergoes sudden and rapid deceleration.
To reduce the friction between the webbing belt and the synthetic resin material and improve the ease with which the webbing belt can be pulled out, a resin film is attached to the inner peripheral surface of the through hole in the through anchor. The frictional resistance of the surface of the resin film with respect to the webbing belt is smaller than the frictional resistance of the inner peripheral surface of the through hole with respect to the webbing belt.
The resin film is basically manually attached by a worker, but it is not easy to attach the resin film to an appropriate position on the through anchor. This is because the through hole of the through anchor is a very narrow and long slit extending along the width direction of the webbing belt, and it is difficult for the worker to determine the length of the resin film on the side opposite from the worker when the resin film is passed through the through hole.
In view of the aforementioned facts, an object of the present invention is to provide a through anchor in which a low-friction member, e.g. a resin film, can be attached to an appropriate position.
A first aspect of the invention is a through anchor comprising: a through anchor body that includes a through hole, through which the webbing belt passes, and a support, which is molded using a metal mold and forms part of an inner peripheral surface of the through hole, with a parting line produced during molding being formed on or near the support in the inner periphery of the through hole; and a low-friction member that passes through the through hole and is adhered onto the support, the low-friction member including modified portions and first and second ends in the direction in which the low-friction member passes through the through hole, wherein, by aligning the modified portions with the parting line when the low-friction member is passed through the through hole and adhered to the support, the length of the low-friction member in the passing direction from the parting line to the first end and the length of the low-friction member in the passing direction from the parting line to the second end are in a specific proportion.
In the invention of the first aspect, when the webbing belt slides on the low-friction member, frictional resistance of the surface of the low-friction member with respect to the webbing belt is smaller than frictional resistance of the support with respect to the webbing belt.
In the through anchor having the above structure, after the webbing belt passes through the through hole, the longitudinal-direction central portion of the webbing belt is supported by the support, which is formed as a part of the inner peripheral surface of the through hole.
In the through anchor of the present invention, the support is covered with a low-friction member adhering thereon and basically is not exposed. The frictional resistance of the surface of the low-friction member with respect to the webbing belt is smaller than the frictional resistance of the inner peripheral surface with respect to the webbing belt. The low-friction member therefore enables the webbing belt to be pulled out and taken up more smoothly.
The through anchor of the present invention is molded using a metal mold. The molding produces a parting line on or near the support of the inner peripheral surface of the through hole.
The low-friction member includes modified portions. At the time of adhering the low-friction member onto the support, by having the modified portions aligned with the parting line, the proportion of the length of one end side and the length of the other end side of the low-friction member from the central portion of the low-friction member in the direction in which it passes through the through hole is specifically determined.
In this manner, by adhering the low-friction member onto the support with the modified portions aligned with the parting line, the position of the low-friction member relative to the through anchor body can be easily determined.
Still in the first aspect, the low-friction member includes a main body that is adhered onto the support, and at least one fixing piece adhered at a predetermined position on the through anchor body, wherein the at least one fixing piece extends from an outer periphery of the main body and a dimension of the fixing piece in a direction orthogonal to both the thickness direction of the fixing piece and the direction in which the fixing piece extends from the main body is smaller than a dimension of the main body in the orthogonal direction.
In the through anchor having the above structure, the low-friction member is attached onto the through anchor body such that the main body of the low-friction member is fixed onto the support and the fixing pieces extending from the main body are fixed to the through anchor body at positions other than that of the support.
If the low-friction member is to be attached on a curved surface of the through anchor body, a portion of the low-friction member must be curved in the width or longitudinal direction thereof in accordance with the curvature of the curved surface of the through anchor body.
However, if the dimension of the low-friction member is longer than the adhesion surface of the through anchor body in the curved direction thereof, the low-friction member may wrinkle or be lifted partially from the adhering position, and it is not easy to curve the low-friction member in accordance with the curvature of the curved surface of the through anchor body. Therefore, the low-friction member may sometimes fail to be reliably fixed.
In the through anchor of the present invention, a dimension of the fixing piece in a direction orthogonal to both the thickness direction of the fixing piece and the direction in which the fixing piece extends from the main body is smaller than a dimension of the main body in the orthogonal direction. Hence, even if the fixing piece is to be attached onto a curved surface, adhesion can be accomplished without greatly curving-the-fixing piece. Accordingly, the fixing piece can be reliably fixed onto the through anchor body.
Further, in the first aspect, the through anchor body includes a groove formed at a position other than the position at which the support is disposed, a portion of an outer periphery of the low-friction member is inserted into the groove and is fixed to a portion of an inner periphery of the groove, and a width of the groove in a thickness direction of the through anchor body is shorter than a length, in the direction of insertion, of the portion of the low-friction member inserted into the groove.
In the through anchor having the above structure, a portion of the outer periphery of the low-friction member, which is attached onto the support, is inserted into the groove formed in the through anchor at a position other than that of the support, and is fixed to a portion of the inner peripheral surface of the groove.
Note that the dimension of the portion inserted into the groove of the low-friction member in the direction perpendicular to the width direction thereof is larger than the dimension of the opening of the groove in the direction perpendicular to the width direction of the inserted portion. With this arrangement, even if the inserted portion of the low-friction member separates from the inner peripheral surface of the groove and is going to come out from the groove, a surface opposite the surface onto which the inserted portion is fixed prevents the inserted portion from slipping out of the groove.
A second aspect of the invention is a low-friction member comprising: a main body that includes first and second ends and is adhered onto a component; at least one fixing piece that extends from the first end and/or the second end and is fixed at a predetermined position on the component; and a modified portions, wherein the low-friction member includes a central portion between the first and second ends, and when the low-friction member is adhered, the modified portions are disposed at positions where the length from the central portion to the first end and the length from the central portion to the second end are in a specific proportion, and a dimension of the at least one fixing piece in the direction orthogonal to both the thickness direction of the fixing piece and the direction in which the fixing piece extends from the main body is smaller than a dimension of the main body in the orthogonal direction.